The present invention relates to an arrangement for galvanization of treatment goods in a series of baths arranged one after the other. More particularly, it relates to such an arrangement in which the baths are open at their upper sides and provided with covers for selective closing of the upper sides with a suction of vapors located in the bath containers above the liquid level of the bath liquid and with a transporting car for introducing and withdrawing the treatment goods in and from the baths.
Originally the bath containers were left open at their upper side and therefore it had to be taken into consideration that the vapors formed above the baths liquid are dispersed, and can be withdrawn from it only insufficiently. In view of this an arrangement was proposed in the German document DE-OS 3,530,322 in which the upper side of the bath containers or suction devices provided in them can be completely closed by a cover. Air entrance slots are provided almost directly under the upper edge of the suction device in its wall. The cover has walls provided underneath and serving both for centering and insertion of the cover. In the closed condition of the bath containers the walls are located in front of the air suction slot and therefore form a path of increased air resistance in the air path to the suction slots. When the container is open at the upper side for introducing or withdrawing of the goods to be treated, the cover together with the catching shell is removed and displaced to the side. The movement of the cover and the catching shell is therefore coupled. When in the arrangement in accordance with the German document DE-OS 3,530,322 a desired reduction of the exhaust air quantity with the placed cover is achieved, a significant reduction of the exhaust quantity through a tight cover of the total treatment space both in other known arrangements as well as in the arrangement of the German document DE-OS 3,530,322 is disadvantageous. In the first mentioned case damaging gases can escape to the surrounding atmosphere in openings for conductors and current contact rail guides or the like. In the second mentioned case there is a danger that during the aspiration step the negative pressure produced in the container interior or between the suction devices fixes the cover so that its lifting is possible only with overcoming of this negative pressure, in some cases this is difficult. Furthermore, the above mentioned positioning of the suction slot is disadvantageous. A very high portion of surrounding air is aspirated, or in other words the exhaust quantity is correspondingly increased opposite to the desired object. The aspirated air is strongly whirled on the very short path between the upper edge of the suction device and its air suction slots. Furthermore, the region between the suction slots and the upper surface of the bath liquid located in the container is not flown by the suction air, so that the vapors located there are aspirated. During traveling of the treatment goods in the station and removal of the goods, the cover must be lifted. The damaging gases escape especially intensely during the withdrawal. The arrangement of the air slots in accordance with the German document DE-OS 3,530,322 is not favorable for this operational condition, since a greater part of the surrounding air is aspirated. The action of the suction device is therefore very affected and by increase of the aspirated air quantity can be compensated only insufficiently. The above mentioned coupling of the movement of the cover and the movement of the catching shell has also the disadvantage that the associated transporting cars cannot be equipped as spraying cabins with a catching shell which during spraying of the treatment products are located under them.